A model for protein folding has been developed which consists of three hypotheses: 1) the conformational distributions at the equilibrium state is a function of the solution conditions, 2) folding is an equilibrium process of the conformational ensemble under physiological conditions, 3) only after completion of folding of the unit of the amino acid sequence the specific coupling of interatomic interactions comes into existence throughout the structure resulting in binding the polypeptide chain in the ordered state. Refinement of the electron density map of liganded nuclease-T is contemplated for precise interpretation of the effect of ligand binding on the conformational dynamics. We have demonstrated that yeast mitochrondrial cytochrome c synthetase can catalyze the direct covalent bonding of the heme group to the horse apoprotein to form horse cytochromec-like species. Thus, the results may have opened the way for use of cytochrome c synthetase for chemical synthesis of cytochrome c.